I'll try that out! ThanksThe vast majority of your beneficial bacteria is on the large rock. Removing the rubble won't negatively affect it.
I agree with others, get rid of all that rubble that is junking up the sand bed. Just my personal preference though, but I would also separate those rocks a little so the fish can swim through / around each rock. I have never liked the look of 2 or 3 rocks stacked so close together. Could super glue some pieces of rubble to act as spacers a little between the rocks.